Ground-dwelling sciurids, including prairie dogs (Cynomys), marmots (Marmota) and several genera of ground squirrels (e.g. Ammospermophilus, Spermophilus, Notocitellus, Ictidomys, Urocitellus), emit alarm calls in the presence of predators to warn their kin. These calls show high intra- and inter-species variation. The alarm calls of many species have potential to encode information about caller identity, and possibly enable the ground squirrels to recognize unreliable callers or to estimate the degree of risk. The alarm calls can be used to determine species or subspecies, and can also help resolve some taxonomic complexities. and Irena Schneiderová.
The article summarises results of our research on inter- and intra-species variability in alarm calls (emitted in the presence of predator) of the European Ground Squirrel (Spermophilus citellus) and closely related species (Taurus Ground Squirrel - S. taurensis, Anatolian Ground Squirrel - S. xanthoprymnus). Alarm calls of all three species mostly consist of two different elements; individuals producing alarm calls with only one of them were, however, also recorded. Although their alarm calls share the same basic structure, the three species can be clearly distinguished. Significant inter-individual differences allow identification of particular callers in a colony. and Irena Schneiderová, Richard Policht.
Cytochrome P450s (P450s) involved in insecticide resistance reduce the efficacy of insecticide-based vector control by rendering vector control ineffective. They are recorded in many species of vectors and have various constitutive and insecticide induction profiles. In this study, the isolation and prediction of the structure of a P450 from a strain of Aedes aegypti originating from Malaysia is reported. Quantitative mRNA expression of this gene and a previously reported P450, CYP4H28v2, in the developmental stages of the mosquito after exposure to sub-lethal concentrations of insecticides is also reported. The isolated P450, CYP4H31v2, is an allelic variant of CYP4H31 and contains several conserved motifs of P450s. The secondary structure of the protein is mostly made up of alpha helices and random coils. The tertiary structure was generated using homology modeling and was of good quality based on structure validation using protein structure assessment tools. CYP4H28v2 and CYP4H31v2 were differentially expressed in the developmental stages of the vector, with a significantly increased expression in adult males. The genes were significantly over-expressed in larvae exposed to deltamethrin and permethrin for 6 h. In the DDT-treated larvae, only CYP4H31v2 was significantly over-expressed after a 6 h exposure. Under-expression of the genes was predominant in larvae treated with the organophosphates malathion and temephos. Though the functions of these P450s are unknown, their response to induction by exposure to insecticides indicates the likely involvement of these genes in insecticide tolerance. and Fatma M. A. El-Garj, Mustafa F.F. Wajidi, Silas W. Avicor.
Classical biological control is an important means of managing the increasing threat of invasive plants. It constitutes the introduction of natural enemies from the native range of the target plant into the invaded area. This method may be the only cost-effective solution to control the rapidly expanding common ragweed, Ambrosia artemisiifolia, in non-crop habitats in Europe. Therefore, candidate biocontrol agents urgently need to be assessed for their suitability for ragweed control in Europe. A previous literature review prioritized the host-specific leaf beetle Ophraella slobodkini as a candidate agent for ragweed control in Europe, whereas it rejected its oligophagous congener O. communa. Meanwhile, O. communa was accidentally introduced and became established south of the European Alps, and we show here that it is expanding its European range. We then present a short version of the traditional pre-release risk-benefit assessment for these two candidate agents to facilitate fast decision-making about further research efforts. We selected two complementary tests that can be conducted relatively rapidly and inform about essential risks and benefits. We conducted a comparative no-choice juvenile performance assay using leaves of ragweed and sunflower, the most important non-target plant, in Petri dishes in climatic conditions similar to that in the current European range of O. communa. This informs on the fundamental host range and potential for increasing abundance on these host plants. The results confirm that O. slobodkini does not survive on, and is hence unlikely to cause severe damage to sunflower, while O. communa can survive but develops more slowly on sunflower than on ragweed. In parallel, our species distribution models predict no suitable area for the establishment of O. slobodkini in Europe, while O. communa is likely to expand its current range to include a maximum of 18% of the European ragweed distribution. Based on this early assessment, the prioritization and further assessment of O. slobodkini seem unwarranted whereas the results urgently advocate further risk-benefit analysis of O. communa. Having revealed that most of the European area colonized by ragweed is unlikely to be suitable for these species of Ophraella we suggest the use of such relatively short and cheap preliminary assessment to prioritise other candidate agents or strains for these areas., Suzanne T. E. Lommen, Emilien F. Jolidon, Yan Sun, José I. Bustamante Eduardo, Heinz Müller-Schärer., and Obsahuje bibliografii
Aryl hydrocarbon receptor (AhR) and glucocorticoid receptor (GR) play crucial role in the regulation of drug metabolizing enzymes and in many essential physiological processes. Cellular signaling by these receptors shares several functional and regulatory features. Here we investigated regulatory cross-talk between these two receptors. Human hepatoma cells (HepG2) were the model of choice. We analyzed the effects of dexamethasone (DEX) and dioxin (TCDD) on i) expression of AhR and GRα mRNAs; ii) levels of AhR and GR proteins; iii) transcriptional activities of AhR and GR in reporter assays; iv) 7-ethoxyresorufin-O-deethylase activity (EROD). We found that both DEX and TCDD affected AhR and GR mRNAs expression, proteins levels and transcriptional activities in HepG2 cells. These effects on cellular signaling by AhR and GR comprised up-/down-regulation of gene expression and ligand-dependent protein degradation. We conclude that interactive regulatory cross-talk between GR and AhR receptors in HepG2 cells defines possible implications in physiology and drug metabolism. Future research should be focused on the investigation of AhR-GR cross-talk in various normal human cells and tissues both in vitro and in vivo., Z. Dvořák, R. Vrzal, P. Pávek, J. Ulrichová., and Obsahuje bibliografii a bibliigrafické odkazy
Monosodium glutamate (MSG) treatment of neonatal mice results in a selective damage to the arcuate nucleus (ARC) and development of obesity with increased adiposity at sustained body weight in the adulthood. Feeding pattern of the MSG obese mice is unusual. Our previous results showed that after 24-h fasting, MSG mice consumed negligible amount of food in several hours and therefore, it was impossible to register the effect of peptides attenuating food intake such as cholecystokinin (CCK) or cocaine- and amphetamine-regulated transcript (CART) peptide. To overcome this problem, two findings were used: firstly, orexigenic effect of neuropeptide Y (NPY) was attenuated both by CCK or CART peptide in lean fed mice and secondly, orexigenic effect of NPY was preserved in fed rats with MSG obesity. In this study, short-term food intake in fed lean and MSG obese C57BL/6 male mice was measured after simultaneous central administration of orexigenic NPY with either CART peptide or peripherally administered CCK. Anorexigenic action of exogenous CART peptide was preserved in MSG obese mice. On the other hand, satiety effect of exogenous CCK was completely lost in MSG obese mice. In conclusion, effective leptin signaling in ARC is necessary for satiety effect of CCK., B. Železná ... [et al.]., and Obsahuje seznam literatury
Mnoho vědeckých jmen ptáků je odvozeno od antických mýtických jmen. Důvodem je mimo jiné to, že bohové za trest nebo z dalších příčin proměňovali mýtické postavy v ptáky. Příklady uvádí druhý díl seriálu., Many scientific names of birds are derived from ancient Greek and Roman mythical names. One of the reasons is that gods used to turn mythical characters into birds as a punishment or for other causes. The examples are given in the second part of the series., and Tomáš Pavlík.